EP1769897A1 - Apparatus and method for injection and safety device therefore - Google Patents

Abstract

Injection device comprises a nozzle unit (2) and a safety device that is mounted on the nozzle unit and comprises a protective plate (6) that can move relative to the nozzle unit and is designed so that, when the nozzle unit is docked in the feed opening of a mold with the protective plate interposed, flow communication can be established with the injection nozzle (26). Independent claims are also included for: (1) safety device comprising a protective plate that that can move relative to a base element and has a nozzle system; (2) method for operating an injection device comprising a nozzle unit and a safety device comprising a protective plate that can move relative to the nozzle unit during docking and is spaced from the nozzle unit in a withdrawn state, where the nozzle unit and the protective plate form a flow communication in the docked state.

Description

The present invention relates to a device for injection with an injection unit, which comprises an injection nozzle, and a protective device, which is arranged on the injection unit and having a relative to the injection unit movably mounted protective plate, and a protective device for use in particular in such a device, with a Basic element and a relative to this movably mounted protection plate. Likewise, the invention relates to a method for operating a device for injection with an injection unit and a protective device comprising a protective plate, wherein the protective plate is moved in a docking relative to the injection unit and arranged in a raised state spaced from the injection unit.

With injection units, a variety of materials can be processed, such as plasticized plastic, mixed starting materials for thermosets or molten liquid metal. The material is generally injected from an exit opening of the injection unit, in particular an injection nozzle thereof, through a gate into a mold cavity formed between two mold halves of a mold. In the processing of such materials with an injection unit must therefore be ensured that the operator is adequately protected, paying particular attention to uncontrolled leaking from the injection unit material, otherwise it may be in contact with the material, for example, burns or burns come.

Such protection is particularly important when the injection unit docks to the mold such that when the mold is open, the injector faces the operator. This can occur, for example, in so-called multi-component injection molding, in which a further injection unit is often arranged perpendicular to a first in the region of the mold half-separating surface on the side opposite the operating unit is. Uncontrolled leakage of material from an injection unit can occur, for example, as a result of decomposition processes of the material stored in the injection unit, which usually proceeds with evolution of gas. Also, due to a faulty operation or a control error premature spraying done.

Therefore, it is known to position pneumatically or hydraulically operated protective flaps in front of an outlet opening of the injection unit, in particular an injection nozzle of the same, which are opened only shortly before docking of the injection unit to a gate opening of a mold. Docking is here understood to mean the startup of the injection unit or the injection nozzle thereof at a gate opening under application of sufficient pressure, so that a substantially dense flow connection between injection unit and gate opening can be produced and material can be introduced from the injection unit into the mold cavity. Since the protective flaps described are actively driven, an electrical proximity switch must be provided to allow a corresponding control of the protective flap.

This is disadvantageous because in case of failure or malfunction of the electrical proximity switch or the corresponding active drive mechanism a secure protection against uncontrolled escaping material is not guaranteed. In addition, the active activation increases the cycle time, the susceptibility to errors is increased on account of the dependence on active components and, moreover, there is no reliable protection in the periods in which the protective flap is opened or closed.

It is also known to provide a corresponding protective mechanism in an injection nozzle of an injection unit, which is then designed in the manner of a sliding closure nozzle. Such an injection nozzle has a spring-loaded closure torpedo in a nozzle channel, and is designed such that when pressure is applied to a nozzle abutment surface, the closure torpedo in the nozzle channel is displaced against the spring force such that the nozzle channel is opened. Thus, upon contact of the nozzle abutment surface with a gate under pressure, the nozzle channel can be opened and injection from the injection unit through the nozzle channel and the gate in a mold cavity of a mold is possible. When lifting the injection unit and thus the injection nozzle, the closing torpedo is moved within the nozzle channel due to the spring bias in a closed position, whereby the nozzle channel is closed and no further material leakage is possible. In such a Schiebeverschlussdüse protection against uncontrolled leakage of material due to the forced control by the spring in the off-hook condition is always guaranteed.

The disadvantage, however, is the high susceptibility of the worked on fit mechanical components of this nozzle, which also easily lose their functionality due to contamination. In addition, such a nozzle has long flow paths for the material, which, in particular in the case of a necessary heating, is subject to degradation, as a result of which the quality of the molded parts produced suffers. Internal deflection channels, which conduct the melt around the closing torpedo, additionally degrade the melt quality. Further disadvantages arise from the fact that the material is trapped by the sliding closure nozzle in the injection unit, which can lead to procedural problems.

A controlled emptying of the injection unit, which may be necessary, for example, to dispose of residual material in material changes of still contaminated or not very high quality material directly after a change of material or even when restarting after a longer life, is difficult when using a Schiebeverschlussdüse. In order to allow the material to be sprayed against a suitable surface or into a suitable space, a special lock must be attached to the sliding closure nozzle so that the closure torpedo remains in an open position even when it is lifted off. In addition, the injection unit must be positioned in front of a baffle plate or on a collecting container, so that a simple spraying is possible.

Alternatively, it could be hosed down by the open mold under contact with the gate, but this means a heavy contamination of the mold with a corresponding cleaning effort. A further disadvantage is that such a sliding closure nozzle has high manufacturing costs due to the large number of cooperating fitting parts.

From the DE 103 18 826 B3 a splash guard for an injector of an injection molding machine is known, which has a protective plate which is reversible between a nozzle channel of the injection unit releasing the opening position and a cover this cover. Here, the reversal takes place by a mechanical switching mechanism, which acts on a form between this and the protective plate transmitting force when docking the injection unit. The mechanical switching mechanism in this case has a touch finger movable on contact with the mold, which forcibly controls the switching of the protective plate. The disadvantage of this is that the mechanical components of the derailleur are largely open and thus easily contaminate at the exit of molding compound and are thus prone to failure.

Furthermore, there must be sufficient space on the mold in the region of the sprue opening in order to provide a sufficient contact surface for the mechanical rear derailleur and in particular the sensing finger. In modern forms, however, it is increasingly difficult to ensure sufficiently free contact surface due to additional attachments and facilities, such as tempering and their inlet and Abführleitungen and Kernzügen and the like. A disadvantage of this protective device is further that when spraying into the open for emptying the injection unit in a material change or the like, only small space tolerances are present and a very strong contamination of the protective plate and the actuation mechanism results.

The object of the present invention is therefore to present a device for injecting and usable in a corresponding device protective device that is simple and inexpensive to build with minimal susceptibility to interference and ensures effective protection for the staff. Likewise, a method for operating a device for injecting to be presented, which is easy to operate with low susceptibility and ensuring a high level of security for the operator.

This object is achieved by a device for injecting with an injection unit, which comprises an injection nozzle, and a protective device, which is arranged on the injection unit and a relative to the injection unit movably mounted Protection plate, wherein the protective plate is designed such that when docking the injection unit to a gate opening of a mold with the interposition of the protective plate, a flow connection with the injection nozzle can be produced.

Such an injection device has an injection unit, which may be a separate injection unit, for example in the manner of a piston injection unit or else a combined unit, for example in the manner of a screw plunger injection unit. The injection unit has an injection nozzle, through which the material to be processed can be injected from the injection unit through a gate opening into a mold cavity of a mold. A protective device arranged on the injection unit has a protective plate movably mounted relative to the injection unit, which shields any operating personnel in the event of an uncontrolled discharge of material from the injection unit. The protective plate is also designed such that upon docking of the injection unit to a gate opening of a mold, a flow connection with the injection nozzle of the injection unit with the interposition of the protective plate can be produced. For this purpose, the protective plate may, for example, have a small passage opening, which in the docked state can be brought into coincidence with the injection nozzle such that material can be transported from the injection nozzle through the passage opening to the gate opening via a flow connection. Such a passage opening is the simplest case of a nozzle. Preferably, the passage opening may be designed such that their dimensions correspond to the dimensions of the injection nozzle and their diameter is not greater than that of the nozzle channel of the injection nozzle.

The protective plate is in not docked, so lifted state by their movable storage relative to the injection unit storable such that it is spaced from this. Thus, it can offer effective protection against leaking material, since the passage opening or other means for establishing a flow connection with the injection nozzle are preferably dimensioned such that at a spacing there is no risk of material passing through it. Escaping material bounces off the protective plate.

By means of the device according to the invention, operating personnel who are in the area of the injection nozzle of an injection unit can effectively prevent uncontrolled escaping material to be protected. Such protective mechanisms are particularly important in the case of multi-component injection molding of great importance, in which additional injection units may be provided for example in the so-called L or V positions. Here, an injection does not take place as in standard distributed one-component injection molding machines by a platen in the mold cavity, which already have a certain type of splash guard in that uncontrolled spurting material is emptied in dosed injection unit in a spatially narrow area between injector and platen. In the L position, the injection unit can be arranged horizontally on the mold at right angles to the closing direction thereof. An injection can be done with a closed mold either by a runner in the mold parting plane, or by a, preferably provided in the stationary mold half, runner. In the V-position, the injection unit is usually arranged vertically above the mold, injection is also preferably carried out in the region of the mold parting plane or by a separate, provided in the mold runner.

In particular, in an injection in the region of the parting plane, in the open mold, the injection unit in the case of the L-position directly to the operator located on the opposite side. In the V-position, such material is injected uncontrollably into the open tool room, which is accessible to the operating personnel, as well as the operating area in front of it. The operating personnel can accordingly be injured very easily by uncontrollably escaping, hot and / or corrosive material.

Preferably, the protective plate can be displaceably mounted in the docking direction relative to the injection unit, this being a linear movement. This has proven to be particularly advantageous in that no complex pivoting or tilting movements are to be made, which are error-prone and expensive in mechanics. In addition, during docking of the injection unit, there is already a relative movement between the injection unit and the molding tool, which can be exploitable in this direction when the protective panel is displaceable. Due to the displaceability of the protective plate with respect to the injection unit in the docking direction, effective protection can be ensured even with relatively small expansions of the protective plate, since only one area can be covered by the protective plate in which uncontrolled escaping material can arise. Also already occurs at small intervals the protective plate from the injection unit a high protective effect, since a passage of material through the protective plate is rapidly unlikely. In addition, a linear movement is easy and can be done in short times. In this context, it should be noted that a protective plate does not necessarily have to be planar, but that this is understood to mean a substantially flat but not necessarily flat element. Thus, a protective plate may also have a curvature or other shapes.

According to one embodiment of the invention, the protective plate may have a nozzle system, via which the flow connection can be produced. At this point, the injection nozzle of the injection unit can be docked via the nozzle system to produce a flow connection therefrom to a gate opening of a mold. This has also proven to be advantageous because a separate nozzle system can be designed such that it optimally matches the gate opening of the mold, whereby, inter alia, leaks are reliably avoidable. Furthermore, such a nozzle system can advantageously be designed such that a particularly favorable docking of the injection nozzle to the nozzle system is possible. This can for example be provided by providing a corresponding, preferably substantially conical recess into which the injection nozzle is simple and substantially self-aligning retractable, so that a sealing connection between an outlet opening of the injection nozzle and an inlet opening of the nozzle system can be ensured. Such a nozzle system may, for example, also comprise a plurality of individual nozzles which over-tune with a plurality of sprue orifices of the mold, wherein there is a branch in the nozzle system for material fed from the injection unit through the injection nozzle into the nozzle system.

In a device according to the invention means may be provided to space the protective plate relative to the non-docked injection unit. By this means, a spacing of the protective plate from the injection unit in a non-docked state can be ensured. The protective plate then acts essentially in the manner of a baffle plate for uncontrollably escaping, impinging on them material. For example, pressure cylinders or similar means can be provided as spacing means. The spacing means may be substantially symmetrical to a melt passage, in particular to an axis of symmetry of the injection unit, be arranged, or attack, for example, only asymmetrically.

According to a particularly advantageous embodiment of the invention, the spacing means can be configured as a passive system. By this is meant that an automatic spacing between the injection unit and the protective plate in an unloaded state of the protective plate can be ensured. This is particularly advantageous in that no control is provided which causes a spacing of the protective plate from the injector in the non-docked state. As a result, on the one hand, further time savings can be achieved by reducing the cycle time and an additional source of error can be switched off. Because by passive spacing means the spacing of the protective plate of the injection nozzle in the lifted state and thus the functionality of the protective plate as shielding of the operating personnel can be ensured safely.

The passive spacing means can advantageously be actuated by the docking process itself, so that when the injection unit is docked onto a sprue opening of a mold, the protective plate is moved towards the injection nozzle of the injection unit such that a flow connection with the injection nozzle can be established. This is particularly advantageous when the protective plate is mounted displaceably in the docking direction relative to the injection unit. In a docking operation, the protective plate after contact with the mold against the force of the passive spacing means in the direction of the injection unit can be moved. When completely docked, the protective plate or, where appropriate, its nozzle system abuts against the mold and a flow connection is established between the injection nozzle of the injection unit and the protective plate so that material can be injected through the gate of the mold into a mold cavity.

Particularly advantageously, the spacing means may comprise a, in particular passively configured, compression spring system. Compression springs are mechanically simply constructed, fault-tolerant systems, which are also cheap and available as mass-produced, so that the device is particularly simple and inexpensive to operate.

The nozzle system of the protective plate may preferably comprise a nozzle receptacle and a screw-in nozzle screwed into this nozzle receptacle. This is advantageous since these are standard components which are prefabricated and available in various sizes, whereby the nozzle system is easily and flexibly adaptable to any desired injection nozzles and sprue openings or molds. The modular design also facilitates the operability of the device with different shapes having different sized gate openings.

Particularly advantageously, the nozzle system of the protective plate can be designed to be heatable. This offers itself especially in the processing of thermoplastic material or of metal melts, wherein preferably a separate control of the heater can be given. Alternatively, when processing thermosets, a cooling system for the nozzle system may also be provided. In an advantageous embodiment, a heating band is provided on the nozzle system, which is easily adaptable to the respective nozzle shape and easy to operate, and has a small footprint. Such a heating band may preferably be provided with an integrated thermocouple, which further facilitates the separate controllability.

In the device according to the invention, according to an advantageous embodiment, the protective device can be attached to a nozzle device of the injection unit, which comprises the injection nozzle. By such a mounting of the protective device in the vicinity of the injection nozzle, a relatively compact design of the protective device and the device as a whole can be ensured. In addition, in the case of non-symmetrical attachment only relatively small lever moments occur, and even with symmetrical mounting can ensure a small overall extent. Preferably, the protective device can be fastened to the nozzle device via angle elements or similar fastening means. Advantageously, a minimization of the heat flow from the generally heated nozzle device of the injection unit to the protective device can be effected by the attachment via elements of low material thickness.

In an apparatus according to the invention, an electrical proximity switch may be provided for monitoring. By means of this can be monitored whether in one undocked state there is a gap between the protective plate and injector. Preferably, the proximity switch can directly monitor the movement of the protective plate and be provided, for example, in the region of spacing means. In this way, a jamming occurring in the event of a malfunction of the protective plate relative to the injection unit or a similar malfunction can be detected.

The device according to the invention can be operated with particular advantage purely mechanically, whereby an even higher protection by the protective device can be ensured. At the same time a dual function is provided by the protective device with its protective plate, since it can serve on the one hand to protect the operator from unintentionally leaking material and as a baffle plate for the controlled spraying of excess material, for example in the case of material changes. In these cases, the injection unit is in an off-hook condition, the guard plate is spaced from the injection unit and its nozzle, and upon leakage or spewing of material, it is deflected substantially downwardly by the guard plate. Here, the provided in the protective plate for producing a flow connection in the docked state passage opening or the corresponding nozzle system are dimensioned such that substantially only in direct contact with the injection nozzle, a passage of material is possible. Thus, the protective plate acts as a baffle plate in these cases, from which the ejected material rebounds and is deflected into a machine installation space or there preferably to be provided for collecting material.

Thus, in addition, a trough for receiving hosed material directly on the protective plate and here preferably in a lower region thereof could be arranged. After such a spraying the protective plate is easy to clean and in a next injection step can be done again docking of the injection unit with the interposition of the protective plate.

Likewise, the object is achieved by a protective device for use in particular in a device described above, comprising a base member and a relative to this movably mounted protective plate, wherein the protective plate according to the invention comprises a nozzle system. By providing the nozzle system, such a protective plate can have an intermediate position even during an injection process take what has proven to be particularly advantageous due to the simplicity of the mechanism to be provided, the high reliability and high protection. In this case, a passage opening can also be understood as the simplest embodiment of a nozzle.

Advantageously, means are provided for spacing the protective plate from the base element. Such a basic element can be designed, for example, as a support frame, on which on the one hand the spacing means can be supported, but on which fastening means can also be attachable in order to make the protective device connectable to other elements, for example an injection unit or a mold. The basic element can also be designed in two or more parts in order to enable a symmetrical attachment of the protective device, for example, to an injection unit.

Particularly advantageously, the spacing means may be formed as a passive system, which is understood to mean an automatic assumption of a spaced state between the base element and the protective plate in the absence of external constraint. So it is forceful to reduce the spacing. As a result, the protective function of such a protective device can be ensured particularly simple.

Preferably, the spacing means may comprise a compression spring system, wherein a compression spring system may comprise one or more compression springs. These can attack on the one hand on the base element and on the other hand on the protective plate or on connected thereto elements. Compression springs are mechanically simple, low error prone and standard available components.

Furthermore, the spacing means may comprise at least one bolt on which the protective plate can be arranged. For example, the bolt can be connected to the base element with the interposition of a compression spring system. For such a bolt or similar elements guide devices may be provided to ensure easy movement of the protective plate relative to the base member and to effectively avoid canting or the like.

Advantageously, a housing may be provided which at least partially accommodates the spacing means. By such a housing contamination during operation can be substantially prevented, and a secure mounting of the spacing means or the protective plate relative to the base element can be ensured. In the case of an intended symmetrical attachment and such a housing may be formed in two or more parts, so that, for example, a housing part in each case at least partially receives a part of the base member, a bolt and a compression spring.

The nozzle system of the protective plate may preferably comprise a nozzle holder and a screw-in nozzle, whereby the specification of the nozzle system can be easily adapted to the respective requirements and, for example, operability with changing injection units and gate openings of molds can be ensured. Because of this variability of the nozzle system, easy retrofitting of the protective device is also possible.

Preferably, the nozzle system is heated, but it can also be equipped with processing of, for example, thermosetting media with a cooling device.

On the nozzle system, a space-saving and easily operable heating band can be provided, which may preferably have an integrated thermocouple. Thus, a separate temperature control of the nozzle system depending on measured values can be provided.

Also, an electrical proximity switch, in particular in the region of the housing may be provided. By means of the same, the distance from the housing or the base element, to which the housing is advantageously secured, to nearby borders, such as a shape or even to the protective plate, be measurable. Alternatively, for example, the proximity switch may also monitor the movement of the spacing means to control the movement of the guard plate. The measured values can be used to guarantee a fault-free function of the protective device by providing an error signal for non-positive measured values can be output, whereby, if necessary, a comparison with other measured values is possible.

A protective device according to the invention may further comprise fastening means, which are preferably attachable to the base member and via which an attachment to other elements, for example on an injection unit and in particular on the nozzle device, is possible. Such fastening means may for example be designed in the manner of angle plates, whereby a low heat coupling between the various elements can be ensured.

In the area of the protective plate, a trough can be arranged to make it possible to catch the material dripping off during operation or sprayed off against the protective plate.

According to a particularly advantageous embodiment of the present invention, the protective plate may be chromed. Residues, such as hardened plastic material, can be easily removed from a chrome-plated protective plate, and the thermal conductivity ensures rapid cooling of the residues and a clean and safe functioning can be ensured.

The present invention also relates to a method of operating a device for injection, which is particularly advantageous also for injection into a tool with an injection unit in L or V position usable.

Such a method of operating an injection device comprising an injection unit and a protective device comprising a protective plate, wherein the protective plate is moved in a docking relative to the injection unit and arranged in a raised state spaced from the injection unit, and wherein the injection unit and the protective plate in the docked state form a flow connection, also solves the task. Such a method can be used in particular for operating a device described above.

In this method, the protective plate is arranged in front of the injection unit in such a way that operating personnel are protected from damage by uncontrolled escaping material from the injection unit. In a docking operation, the injection unit in brought an injection position, in this position, the injection unit or an injection nozzle of the same cooperate with a gate opening of a shape that a flow connection between the injection nozzle and a mold cavity of the mold is made. In the docking operation, the protective plate according to the invention is thus moved relative to the injection unit so that it forms a flow connection with the injection unit in the docked state. By means of this flow connection, for example, plasticized material can be injected from the injection unit into a mold cavity.

By contrast, in an off-hook state of the injection unit, and preferably already during lift-off thereof from the mold, the guard plate is spaced from the injection unit. It is then arranged so that there is a certain gap between the injection unit and the protective plate. The advantage of this is that the protective plate does not have to be moved out of the injection direction or docking direction of the injection unit substantially, but can remain in this, so that uncontrolled escaping material impinges on the protective plate and then dripping off of this. The dripping takes place in an area of the machine that is not directly accessible to the operating personnel during operation. Thus, at no time a significant threat to a control position occur. In addition, so simple, substantially linear movement can be ensured, which in turn reflected in short cycle times and low error rate.

Particularly advantageously, the flow connection can be made by means of a nozzle system which is provided in the protective plate. In this way, a particularly secure flow connection can be made, which has little risk of leakage, as can be ensured by an interposed nozzle system particularly good docking on the one hand the injection unit to the nozzle system and the other part of the nozzle system to a gate opening of a mold. A further advantage is that such a nozzle system can be constructed from standard components, so that a simple, technical retrofitting and adaptability to different requirements is given.

According to a preferred embodiment of the method for operating an injection device, the protective plate is spaced apart when the injection unit is lifted off of a mold automatically from the injection unit. By this automatic spacing, an effective protection of the operating personnel can be ensured in each step of the process, since the protective plate when lifted substantially immediately spaced from the injection unit and acts as a shield that shields the operator from an outlet opening of the injection unit. The dimensioning of the nozzle system of the protective plate is chosen such that due to the automatic spacing of a possible passage of ejected material can be excluded by the nozzle system de facto.

Preferably, in the method according to the invention, a proximity switch is used, which measures whether the protective plate is spaced from the injection unit. If the injection unit is not docked to a mold and the protective plate is not spaced from the injection unit at the same time, an error message is generated, since then there is no sufficient protection for the operator by the protective plate. The processing of the recorded signals and the output of the alarm are preferably carried out by a control device. Such or further proximity switches can also fulfill other tasks. For example, it can provide more accurate information about the distance of the injection unit from the mold that can be used by the controller to precisely control the injection unit or the like.

Particularly advantageously, the protective plate in the off-hook state can also serve as a kind of baffle plate against which excess material can be hosed off in a controlled manner. Excess material can be present in an injection unit, for example, before a material change or after long waiting times, which often go hand in hand with degradation of the material. The advantage of this is that no separate baffle plate must be mounted in front of the outlet opening of the injection unit, but that the existing protective plate, which ensures the safety of the operator, can be used twice. The thus controlled against the protective plate sprayed material can be collected below this in suitable containers or even drip only in the engine room.

Before a new injection process, the protective plate can be easily cleaned, for example, of residues, so that in the docked state again a flow connection between injection unit and protective plate and material can be injected into a mold cavity.

By means of the device according to the invention or the method according to the invention, an effective protection of the operating personnel can be ensured in a simple manner while at the same time being very low in susceptibility to errors. In addition, the protective device is characterized by simple construction, is low maintenance and can be provided inexpensively, in particular, it is also easy to retrofit in already in operation located injection units. In addition, it is time-optimized in operation, since no time cushion for a Ausschwenkvorgang the protective plate, which remains consistently in front of the injection unit, must be provided. The protective plate carries, so to speak, a free-floating nozzle, which is moved up to the injection nozzle of the injection unit when docking.

Alternatively, it is also conceivable that a protective plate according to the invention can be held in certain constellations on a mold and not on an injection unit.

Fig. 1:

eine erfindungsgemäße Vorrichtung zum Einspritzen in der Seitenansicht,

Fig. 2:

einen Ausschnitt einer solchen Vorrichtung in einer Frontansicht,

Fig. 3:

einen Ausschnitt einer solchen Vorrichtung in der Draufsicht,

Fig. 4:

eine alternative Vorrichtung zum Einspritzen in der Schnittdarstellung von der Seite, und

Fig. 5:

diese Vorrichtung in einer Schnittdarstellung von oben.

An embodiment of the present invention will be explained in more detail with reference to the following figures. Show it:

Fig. 1 :

an inventive device for injection in the side view,

Fig. 2 :

a detail of such a device in a front view,

3 :

a detail of such a device in plan view,

4 :

an alternative device for injection in the sectional view from the side, and

Fig. 5 :

this device in a sectional view from above.

1 shows a device for injection with a front part of an injection unit 2, which ends in a nozzle device 3. This nozzle device 3 comprises an injection nozzle 26, through which, for example, in the case of plastic injection molding plasticized material can be injected from the injection unit. On the nozzle device 3, a protective device 1 by means of fastening means 22 and spacers 24 is attached. The protective device 1 has a protective plate 6, on which a nozzle system with a nozzle holder 8 and a screw-10 is provided, which can be brought to the injection nozzle 26 of the injection unit 2 to cover. The protective plate 6 has spacer means 16 which comprise bolts 18 and provide for a spacing of the protective plate 6 with respect to a housing 14. The bolts 18 are movably mounted in the housing 14 and displaceable relative thereto in the opposite direction of the arrow 28. The fastening means 22 engage the housing 14. By using fasteners 22 of small diameter, the protector 1 can be thermally decoupled from the nozzle means 3 heated in the case of processing thermoplastic materials substantially.

Fig. 1 shows the injection unit 2 in the raised state, d. H. that it is not docked to a non-illustrated gate opening of a mold of an injection molding machine. For this reason, the protective plate 6 is spaced due to the spacing means 16 of the injection nozzle 26 so that any uncontrolled escaping material rebounds on the protective plate 6 and drips from this substantially perpendicular to the engine room.

Fig. 2 shows the device for injection from the front. The protective plate 6 with the nozzle holder 8 and the screw 10 covers the injection nozzle 26 of the injection unit 2. On a nozzle device 3, the fastening means 22 are mounted, which carry the protective device 1 with the protective plate 6. From this representation, it is clear that the protective plate 6 is an effective shield for operators who looks at the injection unit 2 substantially frontally, as often occurs in multi-component injection molding with, for example, horizontally arranged at right angles to the closing unit injection units.

Fig. 3 shows the device according to the invention in the undocked state in plan view. The protective device 1 is mounted above the nozzle device 3 of the injection unit 2. The injection nozzle 26 is spaced from the nozzle system of the protective plate 6 with nozzle holder 8 and screw-10. The spacing of the Protective plate 6 of the nozzle device 3 via spacer means 16, the bolts 18 include. These can be kept in the extended position, for example, by a compression spring system not shown in detail in the housing 14.

Fig. 4 shows an alternative device for injection in the sectional view from the side. Elements which correspond to the elements already shown in FIGS. 1 to 3 are designated by corresponding, primed reference numerals. In the sectional view can be seen the operation of the spacing means 16 '. By a compression spring 20 'bolt 18' relative to the housing 14 'is pressurized, so that the protective plate 6' automatically assumes a position spaced from the housing 14 'in the unpressurized, ie lifted, state. The nozzle system with nozzle holder 8 'and screw-10' of the protective plate 6 'is heated separately and has according to this embodiment, a heating cable 12' with integrated thermocouple on. In addition, FIG. 4 schematically shows the position of the nozzle system with nozzle receptacle 8 'and screw-in nozzle 10' in a docked state. The bolts 18 'are moved backwards accordingly. A proximity switch 30 'is arranged to monitor the position of the protective plate 6' on the housing 14 '. The proximity switch 30 'in this case interacts with at least one of the bolts 18'.

In Fig. 5 is a horizontal section through the protective device 1 'shown in FIG. 4, wherein the injection nozzle 26' is not shown in detail. Again, the bolts 18 'are shown in their position in the off-hook and dot-dashed in the docked state. Again, it can be seen how the spacer means 16 'are supported by bolts 18' and compression springs 20 'against the housing 14'.

When docking of the injection unit 2, 2 'to a gate not shown in detail of a form, the injection unit 2, 2' is moved in the direction of the gate, in Figs. 1 and 3, this is indicated by the arrow 28, in Figs 5 is shown by the arrow 28 '. As soon as the nozzle system of the protective plate 6, 6 'hits the gate, the protective plate 6, 6' is displaced relative to the restoring force of the spacer means 16, 16 'due to the continuous docking movement of the injection unit 2, 2', until the injection nozzle 26, 26 'in turn docks to a correspondingly shaped sprue position of the nozzle system of the protective plate 6, 6'. This is particularly apparent from Fig. 4, in the docking state is shown schematically. Between the nozzle receptacle 8 'and the injection nozzle 26', a flow connection is made here. Through this flow connection, material from the injection unit 2, 2 'via the injection nozzle 26, 26' and the nozzle system of the protective plate 6, 6 'with nozzle holder 8, 8' and screw 10, 10 'over the gate of the mold into a shape provided mold cavity are injected. Depending on the docking position on the mold, the injection unit 2, 2 'remain docked in successive injection processes or else be lifted between each individual injection process.

In the case of lifting off, due to the passive spacing means 16, 16 ', the protective plate 6, 6' is immediately spaced from the injection unit 2, 2 ', remaining in contact with the mold until the bolts 18, 18' of the spacing means 16, 16 'Fully extended, only then finds a lifting movement of the protective plate 6, 6' and their screw-in nozzle 10, 10 'from the gate of the mold instead. Thus, an effective functioning of the protective plate 6, 6 'already in the first moments after lifting the injection unit 2, 2' guaranteed, since then already a distance between the protective plate 6, 6 'and injection unit 2, 2' is given, so that uncontrolled the injection nozzle 26, 26 'leaking material on the protective plate 6, 6' rebounds, and the nozzle system can not penetrate.

A further advantage is that in the spaced state, the protective plate 6, 6 'can be used as a baffle plate for a controlled spraying of hot molding compound.

By using such a spring-loaded protection plate 6, 6 ', effective protection of the operator can be ensured at all times independently of control operations, since safe operation by use of passive, d. H. automatically acting spacing means 16, 16 ', such as compression springs 20', even in de-energized state is guaranteed.

The device according to the invention, the protective plate 6, 6 'and the method are characterized by a high degree of safety for the operating personnel at the same time very low probability of failure due to simple mechanical structure and also allow a conscious and controlled emptying of the injection unit 2, 2 ', whereby no locking of the molding material in the injection unit 2, 2' is required as in the devices of the prior art.

LIST OF REFERENCE NUMBERS

1, 1 '

guard

2, 2 '

Injection unit

3, 3 '

nozzle device

4, 4 '

Injection cylinder

6, 6 '

protection plate

8, 8 '

nozzle receiving

10, 10 '

screw-fit

12 '

heating tape

14, 14 '

casing

16, 16 '

spacing

18, 18 '

bolt

20 '

compression spring

22, 22 '

fastener

24

spacer

26, 26 '

injection

28, 28 '

docking direction

30 '

proximity switch

Claims (30)

Device for injection with an injection unit (2, 2 '), which comprises an injection nozzle, and a protective device (1, 1') which is arranged on the injection unit (2, 2 ') and has a relative to the injection unit (2, 2'). ) has a movably mounted protective plate,
characterized in that
the protective plate (6, 6 ') is designed in such a way that, when the injection unit (2, 2') is docked to a sprue opening of a mold with the interposition of the protective plate (6, 6 '), a fluid connection with the injection nozzle (26, 26') can be produced. Device according to claim 1,
characterized in that
the protective plate (6, 6 ') is displaceably mounted in the docking direction (28, 28') relative to the injection unit (2, 2 '). Apparatus according to claim 1 or 2,
characterized in that
the protective plate (6, 6 ') has a nozzle system via which the flow connection can be produced. Device according to one of claims 1 - 3,
characterized in that
Means are provided to space the protective plate (6, 6 ') with respect to the non-docked injection unit (2, 2'). Device according to claim 4,
characterized in that
the spacing means (16, 16 ') are designed as a passive system. Device according to claim 4 or 5,
characterized in that
the spacing means (16, 16 ') comprise a compression spring system. Device according to one of claims 3 - 6,
characterized in that
the nozzle system comprises a nozzle receptacle (8, 8 ') and a screw-in nozzle (10, 10'). Device according to one of claims 3 - 7,
characterized in that
the nozzle system is heated. Device according to one of claims 3 - 8,
characterized in that
on the nozzle system, a heating band, preferably with an integrated thermocouple, is provided. Device according to one of claims 1 - 9,
characterized in that
an electrical proximity switch (30 ') is provided. Device according to one of claims 1 - 10,
characterized in that
the protective device (1, 1 ') is fastened to a nozzle device (3, 3') of the injection unit (2, 2 '). Device according to one of claims 1-11,
characterized in that
on the protective plate (6, 6 ') a trough for receiving hosed material can be arranged. Protective device for use in particular in a device according to one of claims 1 to 12, having a base element and a protective plate (6, 6 ') movably mounted relative thereto,
characterized in that
the protective plate (6, 6 ') has a nozzle system. Protective device according to claim 13,
characterized in that
Means are provided to space the protective plate (6, 6 ') relative to the base member. Protective device according to claim 14,
characterized in that
the spacing means (16, 16 ') are formed as a passive system. Protective device according to claim 14 or 15,
characterized in that
the spacing means (16, 16 ') comprise a compression spring system. Protective device according to one of claims 14 - 16,
characterized in that
the spacer means (16, 16 ') comprise at least one bolt (18, 18') on which the protective plate (6, 6 ') is arranged. Protective device according to one of Claims 14 - 17,
characterized in that
the spacing means (16, 16 ') are at least partially accommodated in a housing (14, 14'). Protective device according to one of claims 13 - 18,
characterized in that
the nozzle system comprises a nozzle receptacle (8, 8 ') and a screw-in nozzle (10, 10'). Protective device according to one of claims 13 - 19,
characterized in that
the nozzle system is heated. Protective device according to claim 20,
characterized in that
on the nozzle system, a heating tape, preferably with an integrated thermocouple, is provided. Protective device according to one of Claims 13 - 21,
characterized in that
an electrical proximity switch (30 ') is provided. Protective device according to one of Claims 13 - 22,
characterized in that
preferably designed in the manner of angle plates fastening means (22, 22 ') are provided on the base member. Protective device according to one of Claims 13 - 23,
characterized in that
on the protective plate (6, 6 ') a trough can be arranged. Protective device according to one of Claims 13 - 24,
characterized in that
the protective plate (6, 6 ') is chrome-plated. Method for operating a device for injection, comprising an injection unit (2, 2 ') and a protective device (1, 1'), which comprises a protective plate (6, 6 '), wherein the protective plate (6, 6') during a docking operation relative to the injection unit (2, 2 ') and arranged in a raised state spaced from the injection unit (2, 2') is arranged,
characterized in that
the injection unit (2, 2 ') and the protective plate (6, 6') form a flow connection in the docked state. Method according to claim 26,
characterized in that
the flow connection by means of a nozzle system of the protective plate (6, 6 ') is produced. Method according to claim 26 or 27,
characterized in that
at a lifting of the injection unit (2, 2 '), the protective plate (6, 6') automatically, preferably in the docking direction (28, 28 '), spaced therefrom. Method according to one of claims 26 - 28,
characterized in that
a proximity switch (30 ') measures whether the injection unit (2, 2') is docked to a mold, and an error message is generated if the protective plate (6, 6 ') is not lifted off the injection unit (2, 2') in the lifted state ) is spaced. Method according to one of claims 26 - 29,
characterized in that
Excess material controlled with lifted injection unit (2, 2 ') against the protective plate (6, 6') is hosed.

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